Imaging apparatus and driving method thereof

ABSTRACT

A computed tomographic (CT) system includes a gantry having a rotating part including a light source, a light source drive control circuit, a rechargeable battery, and a rotating part interface. The gantry includes a detector, a detector control and signal processing circuit, and an image memory. The rotating part may rotate around a central axis. The CT system includes a gantry table on which the gantry is mounted and which includes a host interface. The CT system includes a motor that may cause the gantry to move within a gantry moving range, and a control unit that may process and display image data obtained from the gantry. The rotating part interface may face the host interface, such that the rotating part and host interfaces are configured to be electrically connected with each other, based on the gantry being at a predetermined position within the gantry moving range.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of PCT/JP2019/050276 filed on Dec.23, 2019, which claims priority to Japanese Patent Application No.2018-242594 filed on Dec. 26, 2018, in the Japanese Patent Office (JPO),and Japanese Patent Application No. 2019-165058 filed on Sep. 11, 2019,in the JPO, the entire contents of each of which are incorporated hereinby reference.

BACKGROUND 1. Technical Field

Example embodiments relate to an imaging apparatus such as a computertomographic (CT) system and a driving method thereof enabling highspatial, timing and energy resolution with smaller form factor and lowerpower consumption.

2. Related Art

An imaging apparatus, for example, an X-ray computed tomographic (CT)system comprises a gantry including a rotating part that rotates aroundan imaging target, a bed on which a subject is placed so as to passthrough the inside of the gantry in the direction of the central axis ofthe rotation, a moving bed supporting member, and a slip ring around therotating part enabling an electrical connection with an operation andmonitoring console which reconstructs the subject image using the imagedata transferred via the slip ring. Inside the rotating part, a detectorcomposed of a group of a large number of image pickup elements, acircuit board for processing signals from the detector, an X-raygenerating part at a position facing each other across an imaging objectsuch as a subject, cooling fan, and a high-voltage power supply circuitare incorporated. A conventional CT system is a large, heavy, andexpensive image diagnostic equipment. In addition to the costs of thebuilding where the CT system is installed including the cost of a largepower supply and air conditioning systems, also maintenance cost to keepthe CT system with optimal performance and conditions at all times causea heavy financial burden.

SUMMARY

Some example embodiments provide X-ray CT systems having reduced sizeand cost, which will contribute to the health maintenance of people allover the world. Particularly, it is desired to detect cancers and otherdiseases in their early stages and reduce the increasing medicalexpenses. Even in developing countries, other remote areas anddepopulated areas, it is necessary to provide the latest and highestlevel of medical services to eliminate the medical disparities resultingfrom natural disasters and regional conflicts. Various unsolvedtechnical problems, such as increased size and cost of a CT system,still remain and an effective breakthrough has not been found yet. Oneof the factors that hinder the downsizing of conventional CT system maybe the difficulty to reduce the size and weight of the gantry. The innerdiameter of the rotating part in the gantry is required to be an innerdiameter dimension such that a human body can move and pass in the bodyaxis direction with a margin, for example, an inner diameter of 80 cm ormore. The outer diameter of the gantry usually exceeds 100 cm becausethe X-ray source and detector parts must be installed. Generally, adetector, a detector signal processing circuit, an X-ray source, anX-ray source drive control circuit, and cooling fan need to rotateinside the gantry. However, the X-ray source, the X-ray source drivecontrol circuit, the air-cooling fan, for example, are heavy weight.Therefore, it should be necessary to suppress vibrations and noisesassociated with the rotation and to minimize adverse effects on theentire system caused by the inertial moment of the heavy componentsrotating at a speed of 1 to 2 revolutions per second on a circle with adiameter of 80 cm or more. Furthermore, in order to move the subject inthe body axis direction, it is necessary to move the bed on which thesubject is placed forward or backward at a predetermined speed.Considering the variety of subjects and their weight range like severalkilograms to 200 kilograms, the bed moving means also needs to ensurerobustness capable of covering such a weight range and stable movementof the bed. As a result, such a conventional CT system is prevented frombeing used on the bedside of a patient or during surgery. In addition,it is difficult to realize a small medical examination vehicle equippedwith a CT system.

The detector or the like rotates inside the gantry around the body axisdirection at a speed of about 1 to 2 revolutions per second. In order tosupply power or read out an output signal from a detector or the like,transmission and reception of a signal, or transmission or reception ofpower is performed by a mechanical contact means called a slip ring. Forthe electrical connection by the slip ring, it is necessary to keep therotation speed low and to reduce the number of output signal lines fromthe detector. In order to reduce the number of signal lines,serialization of the parallel signal read through the slip ring isadopted. However, when a large amount of image data is seriallytransmitted, the transmission frequency rises, and then it becomesnecessary to develop some custom semiconductor elements such as ahigh-speed line buffer element, for example. With increase in thetransmission frequency, more power consumption and heat generationcannot be avoided. In recent years, the slice width is being widened sothat the wide area can be exposed by one-time X-ray pulse irradiation.As a result, in addition to increasing the weight of the gantry, it alsoneeds to increase the size of the X-ray generator. The light receivingarea (or the number of slices) in the body axis direction is expanded,which increases the light receiving area of the detector used or thetotal number of pixels requiring further increases the speed and thecapacity of data transmission and high-speed real-time recording. A dataprocessing speed exceeding 1 gigabyte/second is required when the numberof slices is 64, for example. In order to record a large amount of datain real time at high speed, it is necessary to use a plurality of harddisks such as RAID (Redundant Arrays of Independent Disks) incombination. In addition to the realization of such high-speed,large-volume data processing, transmission and recording, it is also aproblem to be solved by at least one example embodiment of the inventiveconcepts to reduce the radiation exposure dose of the subject.

The electric power feeding to the X-ray source or the like may cause aproblem. Increasing the slice width, the X-ray source increases in sizeand the amount of current supplied to the X-ray source drive circuit anda high-voltage generation circuit has tended to increase as an X-raytube current increases. Therefore, the slip ring needs to flow a largeamount of current by sliding the brush on the slip ring, which may causeheat generation and seizure on the contact surface. Therefore,maintenance such as surface polishing of the slip ring and brushelectrode or regular replacement of these parts are required. For the CTsystem installation, new design specifications on the building, floorstrength, air conditioning equipment and their dedicated power supplysystem may be reconsidered. The cost of introducing a CT system is notonly the installation cost of the CT system itself, but also the costrequired for the building including the air conditioning and powersupply system, or regular maintenance cost of the temperature andhumidity management around the system or the entire building throughoutthe year. In the case of use outdoor or at a remote location, alarge-capacity and stable commercial power for the CT system should beprovided, however it may be difficult for a private power generator or abattery to supply enough electric power to the CT system. Therefore, wemay need to use sunlight or other natural energy fully or partially inaddition to the significant reduction of the power consumption and theenergy loss of the CT system. Problems in the CT system to be solved arethe reduction of its size, weight, power consumption, and the periodicmaintenance load as well as enabling the CT system to be used hybridlikefor multiple purposes.

An image pickup apparatus according to at least one example embodimentof the inventive concepts, for example, a CT system has a gantry havinga rotating part that rotates about a body axis direction, a gantry tableon which the gantry is placed, a control part for processing anddisplaying image data obtained from the gantry, and an operating part ofthe CT system. In addition, the CT system has a drive means for movingthe gantry in the direction of the central axis. Further, the rotatingpart has a light source, a light source drive and control circuit, arechargeable battery (also referred to herein interchangeably as asecondary battery, such as a lithium ion battery) for driving thesecircuits, and the rotating part interface. The gantry table has a hostinterface, and the rotating part interface and the host interface areface to face at a predetermined position within the range of the gantrymovement. Preferably, the predetermined position is at the end of thegantry moving range. Or the rotating part interface and the hostinterface are close to each other and face to face in the verticaldirection. Alternatively, the rotating part interface and the hostinterface are close to each other and face to face in the central axisdirection. The rotating part interface and the host interface aremechanically contacted to be electrically connected at a predeterminedposition. Alternatively, the rotating part interface and the hostinterface are close to each other at a predetermined position and areelectrically connected to each other in a contactless manner by aninteraction of an electromagnetic field. Further, a driving means formoving the gantry in the central axis direction is provided inside thegantry. Further, a drive motor for rotating the rotating part isprovided inside the gantry.

A cradle is provided at a predetermined position above the gantry table,and a host interface is located at the cradle. Further, the cradle has atest probe used for testing or calibrating the rotating part, or aholding means for holding a correlation sample. Preferably, the cradlehas a holding mechanism for holding and fixing the rotating part at thepredetermined position, or a cooling mechanism for cooling the rotatingpart. A CT system comprises a gantry having a rotating part, whichrotates about the body or central axis direction, incorporates adetector, a detector control and signal processing circuit for drivingthe detector and processing an output signal of the detector, and animage memory for recording the output signal of the detector. A CTsystem comprises a bed apparatus for introducing a subject into agantry, and a control part for processing and displaying image dataobtained from the gantry, wherein a rotating part includes a lightsource, a light source drive control circuit, and a rechargeablebattery. The CT system has a structure in which the rotating part has arotating part interface and a fixed part around the rotating part havinga host interface being face to face with the rotating part interface.

Inside the rotating part of a CT system, in addition to the light sourceand the light source drive control circuit for driving the light source,at least a detector is placed at a position facing the light source tosandwich the central axis therebetween. Further, a detector drive andits output signal processing circuit, an image memory for recording theoutput signal of the detector, and a rechargeable battery for drivingthese components are incorporated inside the rotating part. Preferably,a lithium ion battery is used as the rechargeable battery. As the imagememory, a large-capacity semiconductor memory, for example, such as adynamic random-access memory (DRAM) or a non-volatile memory like a NANDflash memory may be used. The light source is an X-ray light source or anear infrared (NIR) light source, for example. Preferably, the lightsource is an X-ray light source which employs a carbon nanostructure foran electron beam generating part. The detector is preferably asilicon-based semiconductor sensor, and an analog to digital (AD)conversion circuit is also formed on the silicon-based semiconductorsensor. Preferably, the detector may be a photomultiplier tube typesensor, an avalanche photodiode (APD) type sensor, or a photon countingtype sensor. Preferably, the radiation shielding optical fiber plate maybe provided on the detector, or the radiation scintillator may befurther laminated on the radiation shielding optical fiber plate.Further, the CT system has a wireless interface on the gantry, on thegantry table, on the bed, or on the cradle in order to transmit andreceive a control signal to control the movement of the gantry or thebed in the body axis direction, and to operate the imaging processinside the gantry. A CT system may have the detector being arranged overthe entire inner circumference of the fixed part, and the rotating partmay have an opening at the opposite side of the light source to sandwichthe rotating central axis, the light emitted from the light source isallowed to pass through the opening.

A plurality of induction coils are arranged along the annular part ofthe rotating part, and permanent magnets are arranged along the fixedpart of the gantry that surrounds the rotating part. A CT system mayhave an energy recovery brake circuit in the rotating part, where anelectromotive force in the induction coils, induced by the moment ofinertia about the rotating part, may be converted into the electricenergy and stored. Alternatively, a plurality of induction coils arearranged along the circumference of the fixed part inside the gantrysurrounding the circumference of the rotating part, and the permanentmagnets are arranged along the circumference of the rotating part sothat the N poles and the S poles are alternately placed. Preferably, anenergy recovery brake circuit for converting the kinetic energy of therotating part into an electric energy is connected to the inductioncoils. An electric double layer capacitor may be provided in the energyrecovery brake circuit. Further, the CT system has a wireless interfaceon the gantry side, on the gantry table side, or on the cradle side inorder to transmit and receive a control signal to control the movementof the gantry in the body axis direction, and to operate the imagingprocess inside the gantry. Further, a second gantry is added on thegantry table. A holding means for placing and holding a subject or anobject to be measured is integrally formed with the gantry table. Aguide rail for assisting the movement of the gantry in the body axisdirection is provided on the gantry table. Further, a protective coverfor preventing the subject or the object to be measured from meeting themoving gantry is provided on the gantry table along the moving directionof the gantry. A light source, a detector, an image memory for recordingthe output signal of the detector, or a secondary battery inside therotating part rotating around the body axis may be a cartridge form.Further, the rotating part has a cartridge receiving space having anopening for inserting or removing the cartridge in the direction of thecentral axis in the rotating part. The number of cartridges receivingspaces are set to be larger than the number of cartridges to beinserted.

A method of driving the CT system includes steps, the gantry starts tomove in the direction of the central axis of the gantry, then theoptical signal transmitted through the subject is converted into anelectric signal by the detector and recorded the electric signal intothe image memory while the rotating part is rotating. Then, the movementof the gantry in the direction of the central axis is stopped at apredetermined position, and the electric signal recorded in the imagememory is read out from the rotating part interface through the hostinterface. A method of driving the CT system includes steps, the gantrystarts to move in the central axis direction of the gantry, the lightemitted from the light source is converted into an electric signal bythe detector and recorded the electrical signal into the image memorywhile the rotating part is rotating. Then, in the step of deceleratingthe rotation of the rotating part, the counter electromotive forcegenerated in the induction coil charges into the rechargeable battery orthe capacitor via the energy recovery brake circuit. Alternatively, thegantry of the CT system stops its movement in the direction of thecentral axis at a predetermined position, and then the rechargeablebattery is supplied power charged from the host interface via therotating part interface.

As is discussed in greater detail below, a CT system equipped with adetector array having low noise and low power consumption can berealized using a CMOS type sensor in which a signal processing circuitis integrated on-chip or by laminating an element on the sensor. Inaddition, since an extremely sensitive detector can be used to reducethe amount of the radiation exposure to the subject. Further, thereduction in the size and weight of the CT system and the reduction inpower consumption can significantly reduce the space for installing theCT system, the construction of the building and the power supply, theair conditioning equipment, and the maintenance cost. Further, the slipring and the brush electrode for making an electrical connection withthe slip ring are not necessary, which greatly reduces sparks andbreakdowns to improve the reliability. In addition, the annualmaintenance cost for maintaining the optimal system performance such asperiodical parts replacement and maintenance can be greatly reduced.Furthermore, the rotational moment of the rotating part after eachimaging operation is converted into electric energy to be recovered, andthe recovered electric energy can be reused for the rotational movementat the next imaging operation. As a result, it may reduce the size ofthe built-in rechargeable battery in the rotating part, shorten thecharging time, or increase the number of times of photographing aftercharging. Moreover, since the components in the gantry, such as theX-ray source, the X-ray detector, and the rechargeable battery have acartridge structure, the gantry itself does not need to be disassembledand repaired, and only the defective part is extracted, and a new partis installed instead. As a result, annual maintenance costs andequipment downtime to keep optimal performance of the CT system all thetime may be greatly reduced. By replacing the gantry itself, the lightsource or the detector module according to the diagnostic purposes, itmay not be necessary to install all kinds of image diagnostic apparatuslike X-ray CT and PET (Positron Emission Tomography), for example, asfor the orthopedic surgery, cardiology, and gastroenterology fields.According to at least one example embodiment of the inventive concepts,one hybrid CT system can be applied to various diagnoses in differentmedical fields. Even in an operating room or inpatient ward in ahospital, doctors can quickly and easily determine the initial diagnosisand treatment plan at the bedside without moving emergency or seriouslyinjured patients who were carried in due to an accident. The CT systemcan be made smaller and lighter, and the power consumption or the loadof repair and maintenance can be reduced. Therefore, the CT system canbe moved by a vehicle and enables a quick and accurate initial diagnosiseven in a remote place or in the area hit by a disaster, developingcountries, other remote areas or depopulated areas by providing thelatest and high-level medical services. As a result, the medicaldisparities due to natural disasters or regional conflicts, for example,can be eliminated.

By changing the gantry, the light source or the sensor cartridges, oradding the gantry for PET or the gantry using the near infrared lightsource in one CT system, multi-image diagnosis obtained from differentlight source energies can be realized in a variety of medical fieldssuch as orthopedic surgery, circulatory organ, digestive organdepartments, for example. Further, world-wide advanced medicalactivities will be expanded with the widespread of highly functionalmedical examination vehicles equipped with inspection equipment like theCT system disclosed in at least one example embodiment.

According to at least one example embodiment, a computed tomographic(CT) system may include a gantry including a rotating part. The rotatingpart may include a light source, a light source drive control circuit, arechargeable battery, and a rotating part interface. The gantry mayfurther include, inside or outside the rotating part, a detector, adetector control and signal processing circuit configured to drive thedetector and process an output signal from the detector, and an imagememory configured to record the output signal of the detector. Therotating part may be configured to rotate around a central axis of abody axis direction. The CT system may further include a gantry table,the gantry mounted on the gantry table, the gantry table including ahost interface. The CT system may further include a motor configured tocause the gantry to move in relation to the gantry table in the bodyaxis direction between positions in relation to the gantry table withina gantry moving range. The CT system may further include a control unitconfigured to process and display image data obtained from the gantry.The rotating part interface may be configured to face the hostinterface, such that the rotating part interface and the host interfaceface each other and are configured to be electrically connected witheach other, based on the gantry being at a predetermined position inrelation to the gantry table within the gantry moving range.

The predetermined position may be an end point of the gantry movingrange.

The rotating part interface and the host interface may be configured toface each other in a vertical direction based on the gantry being at thepredetermined position.

The rotating part interface and the host interface may be configured toface each other in the body axis direction based on the gantry being atthe predetermined position.

The rotating part interface and the host interface may be mechanicalinterfaces configured to be electrically connected based on beingmechanically contacted with each other, based on the gantry being at thepredetermined position, or contactless interfaces configured to beelectrically connected in a contactless manner based on an interactionof an electromagnetic field therebetween, based on the gantry being atthe predetermined position.

The motor may be inside the gantry.

The CT system may further include a drive motor configured to rotate therotating part in relation to the gantry. The drive motor may be insidethe gantry.

The CT system may further include a cradle above an upper portion of thegantry table in a vertical direction, the cradle being at thepredetermined position in relation to the gantry table. The cradle mayinclude the host interface.

The light source may be an X-ray light source that includes an electronbeam generating unit, the electron beam generating unit being composedof a carbon nanostructure material.

The detector, the light source, the detector control and signalprocessing circuit, and the image memory may be inside the rotatingpart, and the detector and the light source may be at opposite sides ofthe rotating part such that the central axis is sandwiched between thedetector and the light source.

The detector may be an electron multiplication sensor, an avalancheeffect sensor, or a photon counting sensor.

The control unit and the gantry may have respective wireless interfacesconfigured to enable, by wireless communication between the control unitand the gantry, transmitting and receiving a control signal to controlmovement of the gantry in the body axis direction by wirelesscommunication, or causing the gantry to perform an imaging operation.

The CT system may further include a protective cover above the gantrytable, the protective cover extending along the body axis direction.

Inside the rotating part, at least one of the light source, thedetector, the rechargeable battery, or the image memory may have acartridge form including electrical contacts, and the rotating part mayhave a cartridge receiving space into or from which the at least one ofthe light source, the detector, the rechargeable battery, or the imagememory having the cartridge form is configured to be inserted orremoved.

The CT system may further include a second gantry on the gantry table.

The detector may include a sensor array of sensors that are arrangedover an entire inner circumference of a fixed part surrounding therotating part inside the gantry.

The rotating part may include an opening configured to allow lightemitted from the light source to pass therethrough in the rotating part.The opening and the light source may be at opposite sides of therotating part such that the central axis is sandwiched therebetween.

The CT system may further include a plurality of induction coils,permanent magnets; and an energy recovery brake circuit configured toconvert an electromotive force in the plurality of induction coils,induced by a moment of inertia about the rotating part, into electricenergy. The plurality of induction coils may be arranged along anannular part of the rotating part, the permanent magnets may be arrangedalong a fixed part of the gantry surrounding the rotating part so that Npoles and S poles of the permanent magnets are alternately facing theannular part of the rotating part, and the energy recovery brake circuitmay be in the rotating part, or the plurality of induction coils may bearranged along a circumference of a fixed part inside the gantrysurrounding a circumference of the rotating part, the permanent magnetsmay be arranged along the circumference of the rotating part so that Npoles and S poles of the permanent magnets are alternately facing thecircumference of the fixed part, and the energy recovery brake circuitmay be in the fixed part.

The rotating part interface may be configured to face the hostinterface, such that the rotating part interface and the host interfaceface each other and are configured to be electrically connected witheach other, based on the rotating part being rotated to a particularrotational position where the rotating part interface is at a particularposition to face the host interface.

According to at least one example embodiment, a method of driving the CTsystem may include causing the gantry to begin to move after rotationalmovement of the rotating part around the central axis has started,performing an imaging operation, the imaging operation including X-rayirradiation of the detector by the light source to cause the detector togenerate digital data in response to the X-ray irradiation, recordingdigital data obtained from the detector in the image memory based on theX-ray irradiation, causing a counter electromotive force in theplurality of induction coils to be recovered by the energy recoverybrake circuit as electric energy being caused by rotational kineticenergy of the rotating part, such that the rotational movement isdecelerated while the energy recovery brake circuit charges a capacitoror the rechargeable battery with the electric energy, causing the gantryto stop at the predetermined position, and causing the digital datarecorded in the image memory to be read from the rotating part interfacethrough the host interface.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of example embodiments willbecome more apparent by describing in detail example embodiments withreference to the attached drawings. The accompanying drawings areintended to depict example embodiments and should not be interpreted tolimit the intended scope of the claims. The accompanying drawings arenot to be considered as drawn to scale unless explicitly noted.

FIG. 1(a) is a diagram illustrating a side view of a CT system with aview direction parallel to the X-axis, according to at least one exampleembodiment.

FIG. 1(b) is a diagram illustrating a plan view of the CT system of FIG.1(a) from a top side of the CT system with a view direction parallel tothe Y-axis, according to at least one example embodiment.

FIG. 1(c) is a diagram illustrating a plan view of the CT system of FIG.1(a) with a view direction parallel to the Z-axis, according to at leastone example embodiment.

FIG. 2(a) is a diagram illustrating a plan view with a view directionparallel to the Z-axis direction showing the internal structure of therotating part inside the gantry, according to at least one exampleembodiment.

FIG. 2(b) is a diagram illustrating a block diagram of an electriccircuit, particularly the sensor array and its peripheral circuit usedinside the rotating part of the CT system, according to at least oneexample embodiment.

FIG. 2(c) is a diagram illustrating a block diagram of an electriccircuit, particularly the X-ray generator and light source drivingcircuit used inside the rotating part of the CT system, according to atleast one example embodiment.

FIG. 3(a) is a diagram illustrating a side view of a CT system as seenfrom the X-axis direction, according to at least one example embodiment.

FIG. 3(b) is for explaining a circuit configuration of a wireless powerfeeding part including the non-contact interface, according to at leastone example embodiment.

FIG. 3(c) is a flowchart showing a driving method, according to at leastone example embodiment.

FIG. 4(a) is a diagram illustrating a plan view of the gantry part of aCT system as seen from the Z-axis direction, according to at least oneexample embodiment.

FIG. 4(b) is a diagram illustrating a cross-sectional view seen from theX-axis or Y-axis direction showing the structure of the gantry 5-2 ofthe CT system shown in FIG. 4(a), according to at least one exampleembodiment.

FIG. 4(c) is a diagram illustrating a cross-sectional view seen from theX-axis or Y-axis direction showing the structure of the gantry 5-2 ofanother variation of the CT system shown in FIG. 4(a), according to atleast one example embodiment.

FIG. 5(a) is a diagram illustrating an X-Y plan view of a CT system,particularly the gantry section as seen from the Z-axis direction,according to at least one example embodiment.

FIG. 5(b) is a diagram illustrating a cross sectional structure of theCT system shown in FIG. 5(a) as seen from the X-axis or Y-axisdirection, according to at least one example embodiment.

FIG. 5(c) is a diagram illustrating an enlarged plan view of a portion Aindicated by a broken line in FIG. 5(a), according to at least oneexample embodiment.

FIG. 5(d) is a diagram illustrating a plan view of the opening formed inthe rotating part, as viewed from the X-ray generator, where more thantwo sensor units can be seen through the opening formed in the fixedpart, according to at least one example embodiment.

FIG. 6(a) is a diagram illustrating a plan view of a CMOS solid-stateimage sensor unit suitable for the sensor unit used in a CT system,according to at least one example embodiment.

FIG. 6(b) is another sensor unit also suitable for the sensor unit usedin the CT system, where the CMOS solid-state image sensors are arrangedin close contact with each other as to face each light receiving regionclosely, according to at least one example embodiment.

FIG. 6(c) is a diagram illustrating an enlarged cross-sectional viewshowing the structure of the CMOS solid-state image sensor in FIG. 6(b),according to at least one example embodiment.

FIG. 7(a) is a diagram illustrating a side view of a CT system as seenfrom the X-axis direction, according to at least one example embodiment.

FIG. 7(b) is a diagram illustrating a plan view of the CT system shownin FIG. 7(a), as seen from the Z-axis direction.

FIG. 7(c) is a diagram illustrating an enlarged view of a portion Bindicated by a broken line in FIG. 7(a).

FIG. 8(a) is a diagram illustrating a plan view of a rotating part ofthe CT system showing inside the gantry as seen from the Z-axisdirection at least one example embodiment.

FIG. 8(b) and FIG. 8(c) are diagrams showing partially enlarged viewsshowing the electromagnetic coupling configurations at the portionindicated by the broken line in FIG. 8(a), where the outer circumferenceof the rotating part is surrounded by the inner circumference of thegantry.

FIG. 9(a) is a diagram illustrating a circuit block used inside therotating part of the CT system, particularly showing the energy recoverybrake circuit at least one example embodiment.

FIG. 9(b) is a flowchart for explaining a driving method of the CTsystem using the energy recovery brake circuit.

FIG. 10(a) is a diagram illustrating a cross-sectional view of therotating part used in the CT system as seen from the X-axis directionaccording to at least one example embodiment.

FIG. 10(b) is a diagram illustrating a plan view seen from the Z-axisdirection showing the gantry structure of the CT system according to atleast one example embodiment.

FIG. 10(c) is a diagram illustrating a side view of the CT system asseen from the X-axis direction according to at least one exampleembodiment.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Detailed example embodiments are disclosed herein. However, specificstructural and functional details disclosed herein are merelyrepresentative for purposes of describing example embodiments. Exampleembodiments may, however, be embodied in many alternate forms and shouldnot be construed as limited to only the embodiments set forth herein.

Accordingly, while example embodiments are capable of variousmodifications and alternative forms, example embodiments of theinventive concepts are shown by way of example in the drawings and willherein be described in detail. It should be understood, however, thatthere is no intent to limit example embodiments to the particular formsdisclosed, but to the contrary, example embodiments are to cover allmodifications, equivalents, and alternatives falling within the scope ofexample embodiments. Like numbers refer to like elements throughout thedescription of the figures.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of example embodiments. Asused herein, the term “and/or” includes any and all combinations of oneor more of the associated listed items.

It will be understood that when an element is referred to as being“connected to”, “coupled to”, or “on” another element, it may bedirectly connected to, directly coupled to, or directly on the otherelement, or intervening elements may be present. In contrast, when anelement is referred to as being “directly connected to”, “directlycoupled to”, or “directly on” another element, there are no interveningelements present. Other words used to describe the relationship betweenelements should be interpreted in a like fashion (e.g., “between” versus“directly between”, “adjacent” versus “directly adjacent”, etc.).

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of exampleembodiments. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises”, “comprising,”, “includes” and/or “including”, when usedherein, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof. It should alsobe noted that in some alternative implementations, the functions/actsnoted may occur out of the order noted in the figures. For example, twofigures shown in succession may in fact be executed substantiallyconcurrently or may sometimes be executed in the reverse order,depending upon the functionality/acts involved.

It will be understood that elements and/or properties thereof may berecited herein as being “the same” or “equal” as other elements, and itwill be further understood that elements and/or properties thereofrecited herein as being “the same” as or “equal” to other elements maybe “the same” as or “equal” to or “substantially the same” as or“substantially equal” to the other elements and/or properties thereof.Elements and/or properties thereof that are “substantially the same” asor “substantially equal” to other elements and/or properties thereofwill be understood to include elements and/or properties thereof thatare the same as or equal to the other elements and/or properties thereofwithin manufacturing tolerances and/or material tolerances. Elementsand/or properties thereof that are the same or substantially the same asother elements and/or properties thereof may be structurally the same orsubstantially the same, functionally the same or substantially the same,and/or compositionally the same or substantially the same.

It will be understood that elements and/or properties thereof describedherein as being the “substantially” the same encompasses elements and/orproperties thereof that have a relative difference in magnitude that isequal to or less than 10%. Further, regardless of whether elementsand/or properties thereof are modified as “substantially,” it will beunderstood that these elements and/or properties thereof should beconstrued as including a manufacturing or operational tolerance (e.g.,±10%) around the stated elements and/or properties thereof.

When the terms “about” or “substantially” are used in this specificationin connection with a numerical value, it is intended that the associatednumerical value include a tolerance of ±10% around the stated numericalvalue. When ranges are specified, the range includes all valuestherebetween such as increments of 0.1%.

In at least one example embodiment of the inventive concepts, the gantryor the bed movement direction, that is, the body axis direction isdefined as the Z-axis, and the plane perpendicular to the Z-axis isdefined as the X-Y plane. With reference to the FIGS. 1(a)-1(c), a CTsystem 100 is described according to at least one example embodiment.The FIG. 1(a) shows a side view of the CT system 100 as seen from theX-axis direction. The CT system 100 has a structure including a gantrytable 7, pedestals (9-1 and 9-2) supporting the gantry table 7, and agantry 5 movable in the Z-axis direction on the gantry table 7, suchthat the gantry 5 is movable in relation to the gantry table 7 in theZ-axis direction between various positions in relation to the gantrytable 7 within a gantry moving range. A rotating part 23 with a rotationcenter axis 1 (also referred to herein as a central axis of the Z-axisdirection) is placed inside the gantry 5. An operation and control part,also referred to herein interchangeably as a control unit 40-1, and adisplay monitor 40-2 are provided. The control unit 40-1 and the displaymonitor 40-2 are communicatively coupled to each other as shown in FIG.1(a), such that the display monitor 40-2 is configured to display imagesbased on signals generated at the control unit 40-1 and transmitted tothe display monitor 40-2. The control unit 40-1 is communicativelycoupled (also referred to herein as electrically coupled) to at leastthe gantry table 7 via cable 40-3. A tomographic image reconstructed byan imaging circuit and software (e.g., by at least the control unit40-1) in response to an imaging operation being performed by some or allof the CT system 100 may be displayed on the display monitor 40-2. Amovable gantry carriage 11 has a drive unit (e.g., gantry carriagedriving motor 17) configured to move the gantry 5 in the Z-axisdirection within the gantry moving range, and wheels 15 are attached tothe lower portion of the gantry 5. Further, as described in detailbelow, the electrical connection means for transferring an electricsignal or electric power between the rotating part 23 in the gantry andthe gantry table 7, host interface 2-1, is shown on the upper part ofthe gantry table and the rotating part side (shown in FIG. 1(c), notshown in FIG. 1(a)) in the gantry 5. The bed 3, on which a subject orother examination objects can be placed, is inserted through an innerside of the gantry 5 in the Z-axis directions. The gantry 5 moves inrelation to the gantry table 7 in the Z-axis direction between positionsin relation to the gantry table 7 within a gantry moving range duringthe examination, and on the other hand, the subject on the bed 3 staysin one place together with the bed 3. With the configuration describedabove, a robust and precise control subject movement means is notrequired, and thus the weight of the CT system 100 itself can bereduced. In addition, as will be described in detail below, the scanningspeed in the body axis (Z-axis) direction of the gantry 5 can beincreased without increasing physical or mental distress and load ofpatients.

FIG. 1(b) shows a plan view of the CT system 100 viewed from the Y-axisdirection. Two rails 13, on which the gantry 5 moves along the gantrytable 7, are laid on the gantry table 7. Using a conductive materialsuch as metal for the rail 13 and the wheels 15, electric power can besupplied to the gantry carriage driving motor 17 installed inside themovable gantry carriage 11, or control signals can be transmitted to andfrom the movable gantry carriage 11. As described above, the hostinterface 2-1 which is an electrical connecting means for exchanging anelectric signal or electric power between the rotating part 23 insidethe gantry and the gantry table 7. The host interface 2-1 is provided ata predetermined position on the upper part of the gantry table 7 withinthe range where the gantry 5 can move. For example, the host interface2-1 may be located at a position that is aligned, in a particulardirection (e.g., in the Y-axis direction) with a predetermined positionof the positions within the gantry moving range to which the gantry 5may be moved in the Z-axis direction, such that the host interface 2-1may be aligned with the rotating part interface 2-2 based at least inpart upon the gantry 5 being moved to the predetermined position. Thepredetermined position, for example as shown in FIGS. 1(a)-1(b), may bean end point of the gantry 5 movable range (also referred to herein asthe gantry moving range) in the Z-axis direction. The predeterminedposition is not limited to the end point of the movable range of thegantry 5 so long as the position will not cause any problems when asubject such as a patient is examined, for example. In this exampleembodiment, the bed 3 is placed above the pedestal 9-1 and 9-2, and thuscan be easily removed. Therefore, instead of the bed 3, a subjectholding means having another shape, for example, a movable stretchertype bed may be used. In addition, it is easy to remove the bed 3, andthen remove the gantry 5 from the gantry table 7. As a result, itbecomes easy to perform the maintenance or replacement of the gantry 5.Further, the light source in the gantry 5 can be easily replaced withanother light source having different energy or wavelength showingdifferent imaging characteristics.

FIG. 1(c) shows a plan view of the CT system 100 viewed from the Z-axisdirection. Inside the gantry 5, a rotating part 23 that rotates aroundthe rotation center axis 1 is attached using ball bearings (not shown inthe figure), for example. Further, a timing belt 21 for rotating therotating part 23 is attached to a gantry rotating motor 19 inside themovable gantry carriage 11. As will be described below, the energyrecovery brake circuit 50 may be incorporated inside the rotating part23. Further, since the rotating part 23 has the rotating part interface2-2, it can be electrically connected to the host interface 2-1 at aposition facing the host interface 2-1 when the rotating part 23 isstationary. Restated, the rotating part 23 may be configured to rotatearound the central axis 1 between various rotational positions, and therotating part interface 2-2 may be configured to face the host interface2-1, such that the rotating part interface 2-2 and the host interface2-1 face each other and are configured to be electrically connected witheach other, based on the rotating part 23 being rotated to a particularrotational position where the rotating part interface 2-2 is at aparticular position to face the host interface 2-1, in addition to thegantry 5 being moved to the predetermined position as described above. Aposition sensor (not shown in the figure) using a Hall effect sensor,for example, can be used so that the rotating part 23 stops rotating ata particular rotational position so that the rotating part interface 2-2stops at the position where the rotating part interface 2-2 face and thehost interface 2-1 face are face to face with each other.

It will be understood that, when the rotating part interface 2-2 faceand the host interface 2-1 face are face to face with each other,opposing, or proximate faces of the rotating part interface 2-2 and thehost interface 2-1 may be understood to be at least partially aligned(e.g., overlapped) in a particular direction (e.g., a direction that isnormal to the proximate faces of the rotating part interface 2-2 and thehost interface 2-1), such as the Y-axis direction in FIGS. 1(a)-1(c),and the rotating part interface 2-2 and the host interface 2-1 may thusbe understood to be face to face with each other. When the rotating partinterface 2-2 and the host interface 2-1 are face to face with eachother, respective terminals and/or connectors of the rotating partinterface 2-2 and the host interface 2-1 may be aligned and configuredto mechanically engage with each other. When the rotating part interface2-2 and the host interface 2-1 are face to face with each other, adistance between the rotating part interface 2-2 and the host interface2-1 over the positions of the gantry 5 in the gantry moving range, andpotentially further over the rotational positions of the rotating part23, may be minimized. The rotating part interface 2-2 and the hostinterface 2-1 may be configured to be electrically connected with eachother when the rotating part interface 2-2 and the host interface 2-1are face to face with each other.

Accordingly, it will be understood that the rotating part interface 2-2may be configured to face the host interface 2-1, such that the rotatingpart interface 2-2 and the host interface 2-1 face each other, based onthe gantry 5 being at a predetermined position in relation to the gantrytable 7 within the gantry moving range. In at least one exampleembodiment, the rotating part interface 2-2 may be configured to facethe host interface 2-1, such that the rotating part interface 2-2 andthe host interface 2-1 face each other and are configured to beelectrically connected with each other, based on the rotating part 23being rotated to a particular rotational position where the rotatingpart interface 2-2 is at a particular position to face the hostinterface 2-1, (e.g., opposing, or proximate, faces of the rotating partinterface 2-2 and the host interface 2-1 are at least partially alignedin a direction that is normal to said opposing faces).

As described further below with reference to at least FIG. 2(b), therotating part interface 2-2 and the host interface 2-1 may be mechanicalinterfaces configured to be electrically connected based on beingmechanically contacted with each other, based at least on the gantry 5being at the predetermined position. As described further below withreference to at least FIG. 3(b), the rotating part interface 2-2 and thehost interface 2-1 may be contactless interfaces configured to beelectrically connected in a contactless manner based on an interactionof an electromagnetic field therebetween, based on the gantry 5 being atthe predetermined position.

Further, a gantry carriage driving motor 17 for moving the gantry 5 inthe Z-axis direction is provided inside the movable gantry carriage 11.The electric power for the driving motor can be supplied from the rails13 as described above, or a secondary battery, also referred to hereininterchangeably as a rechargeable battery, can be built inside themovable gantry carriage 11 instead.

Further, as a moving means for moving the gantry 5 in the Z-axisdirection, as will be described later (FIG. 3(a), for example), anotherconfiguration of towing from the pedestal (9-1 or 9-2) side may be alsoused. With these configurations, unlike the conventional case, therotating means of the rotating part 23 in the gantry can be arranged onthe movable gantry carriage 11, for example. As a result, it becomes notnecessary to fix the gantry to the CT main body, and the gantry can bemoved or removed easily. In this example embodiment, the sensor array 31is incorporated inside the rotating part 23. As is discussed in detailbelow, the sensor array 31 can be placed around the entire innercircumference of the gantry 5, which surrounds the rotating part 23 aswill be shown in FIGS. 4(a)-4(c), for example.

The control unit 40-1 may include any well-known structure forimplementing a CT system control unit,

The control unit 40-1, and/or any portions thereof (including, withoutlimitation, any circuits, units, modules, and/or devices describedherein according to any example embodiments) may include, may beincluded in, and/or may be implemented by one or more well-knowninstances of processing circuitry for implementing a control unit of aCT system, such as hardware including logic circuits; ahardware/software combination such as a processor executing software; ora combination thereof. For example, the processing circuity morespecifically may include, but is not limited to, a central processingunit (CPU), an arithmetic logic unit (ALU), a graphics processing unit(GPU), an application processor (AP), a digital signal processor (DSP),a microcomputer, a field programmable gate array (FPGA), andprogrammable logic unit, a microprocessor, application-specificintegrated circuit (ASIC), and the like. In at least one exampleembodiment, the processing circuitry may include a non-transitorycomputer readable storage device, for example a solid state drive (SSD),or a semiconductor memory such as a DRAM or a NAND flash memory, storinga program of instructions, and a processor, for example a CPU,configured to execute the program of instructions to implement thefunctionality and/or methods performed by some or all of the controlunit 40-1.

In at least one example embodiment, the control unit 40-1 may includewell-known hardware for implementing a CT system control unit,including, without limitation, a processor, also referred to herein asprocessing circuitry, a memory, also referred to herein as anon-transitory computer readable storage device, and one or morecommunication interfaces (e.g., wired and/or wireless communicationinterfaces, transceivers, etc.) configured to communicatively couple(e.g., electrically couple) the control unit 40-1 to one or moreexternal devices. The aforementioned processor, memory, andcommunication interface(s) may be communicatively and/or electricallycoupled to each other via a communication bus. The memory may store aprogram of instructions, and the processor may access and execute theprogram of instructions to implement some or all of the functionality ofthe control unit 40-1.

The display monitor 40-2 may include any well-known device forimplementing a display monitor for a CT system, including alight-emitting diode (LED) display device, organic light-emitting diode(OLED) display device, cathode ray tube (CRT) display device, or thelike. As shown in FIG. 1(a), the control unit 40-1 may becommunicatively coupled to the display monitor 40-2 and may generate andtransmit power and/or control signals to the display monitor 40-2 tocause the display monitor 40-2 to display one or more images.

As shown in FIG. 1(a), the control unit 40-1 may be communicativelycoupled to the gantry table 7 via a cable 40-3 (e.g., a wiredconnection) which may be communicatively coupled (e.g., electricallycoupled) to the host interface 2-1, the rails 13, or any portion of theCT system 100 via conductive elements and/or circuits of the gantrytable 7.

As described herein, in some example embodiments, the control unit 40-1may include one or more wireless communication interfaces, including adhoc wireless network communication interfaces (e.g., Bluetooth®, 5G,etc.) to establish a wireless communication link between the controlunit 40-1 and one or more portions of the CT system (e.g., the rotatingpart 23) without a wired communication link therebetween.

With reference to FIGS. 2(a)-2(c), the internal structure of therotating part 23 of the CT system 100, particularly the electric circuitis discussed in detail. FIG. 2(a) is a plan view of the rotating part 23from the Z-axis direction, showing components used inside the rotationpart 23. A light source such as an X-ray generator 25, a high voltagecontrol circuit 29, a sensor array 31 (also referred to herein as adetector), a sensor peripheral circuit 33, a sensor driving and controlcircuit 41, a digital signal processing circuit (not shown in thisfigure), the image memory 35, the rechargeable battery 27, and therotating part interface 2-2 are placed inside the rotation part 23. A“rechargeable battery,” such as rechargeable battery 27, is alsoreferred to herein interchangeably as a “secondary battery,” such as alithium ion battery. While the light source is described herein as anX-ray generator 25, it will be understood that example embodiments arenot limited thereto: the light source may be an X-ray light source(e.g., X-ray generator) or a near infrared (NIR) light source, forexample. As is discussed in detail below, the X-ray generator 25, therechargeable battery 27, and the image memory 35 may have a cartridgetype structure, which can be easily inserted or removed individually toor from the rotating part 23. Each cartridge and the rotating part 23can be electrically connected by metal contacts between these twoportions. The rotating part interface 2-2 may be a non-contact interfacedescribed below in detail, or a contact interface (also referred toherein as a mechanical interface) using an electrically conductiveelectrode. The X-ray beam 26 emitted from the X-ray generator 25 istransmitted through a subject (not shown in the figure) on the bed 3 andreaches the sensor array 31 (e.g., implement X-ray irradiation of thesensor array 31, where the sensor array 31 may be configured to sensethe incident X-ray beam and generate an output signal (e.g., digitaldata) based on said X-ray irradiation). A weight balance unit whichadjusts the weight balance during the rotating part rotates may beprovided. Preferably, the X-ray generator 25 may be an X-ray generatorusing a carbon nanomaterial such as carbon nanotube (CNT), for example,as a field electron emission source. Using the carbon nano material asthe cold cathode material, preheating may not be required, and then thesize and power consumption of the X-ray generator 25 can be reduced ascompared with the case of conventional X-ray tube, and the high voltagecontrol circuit 29 can be downsized, and a cooling fan can be downsizedor even eliminated. In at least one example embodiment, the sensor array31 is incorporated inside the rotating part 23. Alternatively, as willbe described in detail below, the sensor array 31 may be placed aroundthe entire inner fixed portion of the gantry 5 (FIGS. 4(a)-4(c) andFIGS. 5(a)-5(d), for example), such that the sensor array 31 may beoutside the rotating part 23. In such a case, some of the sensorperipheral circuits, an image memory device, and a host interface, forexample, may be located at the fixed part of the gantry 5 and thus mayalso be outside the rotating part 23.

FIG. 2(b) is a circuit block diagram used inside the rotating part 23,particularly showing the sensor array 31 and its sensor peripheralcircuit 33 explained in FIG. 2(a), which includes a sensor driving andcontrol circuit 41, a signal amplifying and AD converter circuit 43, asignal scanning and control circuit 45, a digital signal processingcircuit 47, and a parallel to serial conversion circuit 49, for example.Some of said circuits may be combined in a single circuit configured toperform the functionality of said circuits. For example, the gantry 5may include a detector control and signal processing circuit thatcombines some or all of the sensor driving and control circuit 41, thesignal amplifying and AD converter circuit 43, the signal scanning andcontrol circuit 45, the digital signal processing circuit 47, and theparallel to serial conversion circuit 49 and may be configured to drivesensor array 31 and process an output signal from the sensor array 31(e.g., an output signal generated by one or more sensor units 30 of thesensor array 31 in response to X-ray irradiation thereof). The sensorunits 30, and thus the sensor array 31, are configured to generate anoutput signal (e.g., digital data) based on X-ray irradiation thereof(e.g., said sensor units 30 may generate an output signal based onphotoelectric conversion of incident light in response to X-rayirradiation of said sensor units 30). As shown in FIG. 2(a) and FIG.2(b), the sensor array 31 has a plurality of sensor units 30 arranged inan arc-shaped and placed regularly in the Z-axis direction in order toincrease its slice number or width. As for the sensor unit 30, inaddition to the conventional TFT type sensor, a small electronmultiplication type sensor (like the Micro PMT element manufactured byHamamatsu Photonics KK), an avalanche effect type (APD) sensor, anamplification type detector, or a photon counting type detector, forexample, can be also used. In addition, a CMOS type sensor whichintegrates an AD conversion circuit, and a signal processing circuiton-chip, for example, can realize high-speed and low-noise signalreading. Since these sensor units 30 have high sensitivity or low noisecharacteristics, the total amount of X-ray irradiation or exposure dosecan be decreased. It also becomes easy to increase the scanning speed inthe Z-axis direction by short-time pulse irradiation. Further, as willbe discussed in detail below, if it is not necessary to further increasethe X-ray irradiation area, the high current flow with high voltagerequired for the X-ray generator will not be increased. In addition toreducing the weight of the rotating part 23 by thinning it in the Z-axisdirection, the stability and durability of the carbon nanomaterial usedas a field electron emission source can be improved. As will bediscussed in detail below, the sensor unit 30 has an on-chipscintillator layer which converts an incident X-ray into a visible lightcorresponding to a band gap of a semiconductor material like a silicon(Si) used for the sensor unit 30. Thus, the sensor unit 30 may generatean output signal based on said visible light (e.g., based onphotoelectric conversion of said visible light).

The output signal from the sensor array 31 (generated, for example,based on the sensor unit 30 being irradiated with X-rays generated bythe X-ray generator 25) is converted into digital data (16 bits, forexample), also referred to herein as “image data,” by the signalamplifying and AD converter circuit 43 and sent to the digital signalprocessing circuit 47 via the signal scanning and control circuit 45. Inorder to directly record the image data sent from the digital signalprocessing circuit 47, an image memory 35 is built in the rotating part23. With this configuration, high-speed memory writing becomes possiblebecause parallel recording can be performed directly on the image memory35 via the bus line 38 without performing parallel to serial conversion.Although a magnetic recording medium can be used as the image memory 35,a semiconductor memory such as a DRAM or a NAND flash memory may bepreferable from the viewpoint of recording speed and reliability. On theother hand, unlike the image capturing step, it may not be necessary toread the image data from the image memory 35 in real time manner. Theimage data can be read out after the image capturing step (also referredto herein as the imaging operation) is completed and after the rotationof the rotating part 23 and the movement of the gantry 5 are stopped.Thus, the image data can be output as a serial data to the rotating partinterface 2-2 via the parallel to serial conversion circuit 49. Withsuch a configuration, the number (e.g., quantity) of terminals in thehost interface 2-1 can be reduced by this serialization. Regarding theelectrical connecting means between the rotating part interface 2-2 andthe host interface 2-1, where the rotating part interface 2-2 and thehost interface 2-1 are mechanical interfaces, there are a plurality ofconnectors inside the rotating part interface 2-2 of the rotating part23, with the shape of a concave structure like a female connectionterminal 6. There are the same number of connection terminals 4 with theshape of a convex structure on the host interface 2-1 side, and then theelectrical connection between the rotating part interface 2-2 and thehost interface 2-1 can be made by inserting the connection terminals 4into the concave shape connection terminals 6 when said terminals arealigned, for example when the respective longitudinal axes of theconnection terminals 4 are aligned with corresponding respectiveconnection terminals 6, also referred to herein as connectors, connectorelectrodes, or the like. Such alignment and insertion, to enableelectrical connection between the rotating part interface 2-2 and thehost interface 2-1 may be enabled when the rotating part interface 2-2and the host interface 2-1 are face to face with each other (e.g., whenthe gantry 5 is at the predetermined position, when the rotating part 23is at the particular rotational position, etc.). Unlike the case usingthe conventional slip ring which is a dynamic mechanical and slidingcontact is used, the image data recorded and stored inside the rotatingpart 23 is moving (e.g., when the imaging operation is being performed)can be readout from the rotating part interface 2-2 to the hostinterface 2-1 (e.g., further readout to the control unit 40-1 forprocessing via electrically connected interfaces 2-2, 2-1 and cable40-3) during the time when the rotating part 23 is stopped. With such aconfiguration, the slip ring having undesirable side effects can beeliminated, and high-speed rotation of the rotating part 23, like 2revolutions per second or more, for example, may be easily obtained. Asensor unit 30 as shown in FIGS. 5(a)-5(d), for example, will bediscussed below. Assuming the number (e.g., quantity) of pixels of thesensor unit 30 in the body axis (Z-axis) direction to be 1000, thearrangement pitch of the pixels to be 50 micron meters (μm), and therotation speed of the rotating part 23 to be 5 revolutions per second,the moving speed of the gantry 5 in the body axis (Z-axis) direction canbe estimated about 25 centimeters (cm) per second. As described above,with reducing the weight and increasing the rotating speed of therotating part 23, the scanning speed in the body axis (Z-axis) directioncan be increased. Therefore, the amount of total X-ray exposure to abody being imaged by the CT system may be reduced without increasing thenumber of slices in the body direction, and image inspection accuracycan be improved by the pixel miniaturization. In addition, thisconfiguration may be also useful for imaging constantly moving organssuch as the human heart.

FIG. 2(c) shows a block diagram showing the X-ray generator 25 (alsoreferred to herein as a light source) and the high voltage controlcircuit 29 (also referred to herein as a light source drive controlcircuit) inside the rotation part 23. The cartridge type X-ray generator25 comprises an electron beam generation cold cathode 25C using carbonnanomaterials and an anode target 25A. The high voltage control circuit29 includes a voltage booster circuit 29-1 and a high voltage controlcircuit 29-2. Preferably, the high voltage control circuit 29 is atransformer-less high-voltage power supply unit of small size, lightweight, and low power consumption using a switching power supply and apower semiconductor. As the rechargeable battery 27 having a cartridgestructure, like a lithium ion battery, for example, can be used. Then,the DC voltage of the lithium ion battery 27 can be boosted by the highvoltage control circuit 29, and a timing controlled high-voltage pulsecan be applied to the X-ray generator 25. The lithium ion battery 27 canbe charged by the circuit monitoring the remaining amount of charges inthe battery and charged by the charger circuit (not shown) via therotating part interface 2-2 and the host interface 2-1 during therotating part 23 being stationary.

Circuits as described herein with reference to any example embodiments,and/or any portions thereof (including, without limitation, the highvoltage control circuit 29, the sensor peripheral circuit 33, the sensordriving and control circuit 41, the digital signal processing circuit47, the parallel to serial conversion circuit 49, and/or the highvoltage control circuit 29) may include, may be included in, and/or maybe implemented by one or more instances of processing circuitry such ashardware including logic circuits; a hardware/software combination suchas a processor executing software; or a combination thereof. Forexample, the processing circuity more specifically may include, but isnot limited to, a central processing unit (CPU), an arithmetic logicunit (ALU), a graphics processing unit (GPU), an application processor(AP), a digital signal processor (DSP), a microcomputer, a fieldprogrammable gate array (FPGA), and programmable logic unit, amicroprocessor, application-specific integrated circuit (ASIC), and thelike. In some example embodiments, the processing circuitry may includea non-transitory computer readable storage device, for example a solidstate drive (SSD), storing a program of instructions, and a processor(e.g., a CPU) configured to execute the program of instructions toimplement the functionality and/or methods performed by some or all ofany of the circuits as described herein.

FIG. 3(a) shows a side view of the CT system 200 as seen from the X-axisdirection according to at least one example embodiment. The partsdifferent from those of above example embodiments described will bediscussed in detail below. As shown in FIG. 3(a), the CT system 200 hasa portion 9-3 which stands upright in the Y-axis direction from thegantry table 7, which is hereinafter referred to as a cradle 9-3. Insidethe rotating part 23, as already described above with reference to FIGS.2(a)-2(c), the parts having the cartridge structure (not shown in thisfigure) are used. The cradle 9-3 has a space (indicated by the brokenline portion 37) for retracting the gantry 5, the rotating partinterface 2-2 of the rotating part 23 inside the gantry 5 is acontactless interface 12, and the host interface 2-1 is a contactlesshost interface 10. These contactless interfaces are close to each otherface to face (e.g., when a distance between the interfaces 10 and 12 isreduced or minimized due to motion of the gantry 5 and/or rotating part23) such that the interfaces 10 and 12 may be configured to beelectrically connected to each other based on an interaction of anelectromagnetic field therebetween due to the proximity of theinterfaces 10 and 12 to each other, and they can perform non-contactpower supply charging the lithium ion battery (e.g., rechargeablebattery 27) inside the rotating part 23 and exchanging data or signalsbetween the rotating part 23 and the host side (e.g., control unit 40-1via the gantry table 7). The arrangement of contactless interfaces ofthe host interface side 10 and the rotating part side 12 being close toand face each other in the direction of the rotation center axis 1 isillustrated in FIG. 3(a). With this configuration, the non-contactinterface 12 can approach the non-contact interface 10 in the directionin which the gantry 5 moves in the Z-axis direction. The gantry 5 has arotating part 23 which rotates around the rotation center axis 1. Thedriving method of the rotating part uses the rotation motor 19 and thetiming belt 21 (not shown in this figure) as described above. An energyrecovery brake circuit (50) may be also incorporated inside the rotatingpart 23 as discussed in detail below. Further, in the case power is notsupplied from the rail 13 for the gantry 5 movement, a rechargeablebattery (not shown) may be used in the gantry 5. In this exampleembodiment, the gantry 5 moves in the body axis (Z-axis) direction bythe gantry traction motor 14 provided inside the pedestal 9-1 or thecradle 9-3, and the gantry traction belt 8 along the gantry table 7.

Besides the contactless host interface 10 as described above, a sampleholder 20 is provided inside the space 37 in the cradle 9-3. The samplecalled a standard object or a phantom, for example, is examined inadvance whether the sensor (e.g., sensor array 31) or the light source(e.g., X-ray generator 25) used inside the rotating part 23 isfunctioning properly or not. Further, an inspection probe (not shown inthe figure) inspecting or calibrating the rotating part 23 may beprovided inside the cradle 9-3. Inside the space 37, a supply port 16for injecting a cooling gas such as air or nitrogen gas in order tolower the temperature inside the gantry 5 is provided. An opening 18,which is fitted into the supply port 16 is provided in the rotating part23. A hold mechanism (not shown in the figure) for holding or fixing thegantry 5 in place in relation to the gantry table 7 may be providedinside the space 37. With this configuration, the gantry 5 can beprotected from mechanical shock when the CT system 200 is transported ormoved. As described above, the cradle 9-3 can provide necessaryfunctions for the stable gantry 5 driving, maintaining safety and systemperformance.

FIG. 3(b) is a block diagram related to electromagnetic induction typewireless power feeding circuits and wireless communication circuits withrespect to the non-contact interface section (10 and 12). As shown inthe figure, the circuit configuration on the contactless host interfaceside (10) includes an AC to DC converter (10-3) that converts acommercial power supply (10-2) (e.g., an external alternating current(AC) power supply network to which the gantry table 7 is communicativelycoupled) into a direct current (DC), and a high frequency inverter(10-4) which outputs a high frequency square waveform. A waveformshaping circuit (10-5) converting the square waveform into a sinewaveform is connected to the primary winding coil L1 (10-1) via aninsulated transformer (10-6) for ensuring safety. On the other hand, thesecondary winding coil L2 (12-1) is connected to a load such as asecondary battery (12-2), also referred to herein as a rechargeablebattery, via a rectifying and waveform smoothing circuit (12-4)converting the high frequency current to a direct current followed by areverse current blocking diode (12-3), for example. The contactlessinterfaces 10 and 12 may be configured to be electrically connected in acontactless manner based on an interaction of an electromagnetic fieldtherebetween, based at least on the gantry 5 being at the predeterminedposition such that the interfaces 10 and 12 are face to face with eachother, such that a distance between the interfaces 10 and 12 is reducedor minimized such that interaction of an electromagnetic field betweenwindings coils L1 and L2 (10-1) and (10-2) is enabled.

As for the transmitting and receiving control signals or image data, awireless communication system based on near-field magnetic fieldcoupling for example, may be used. As shown in FIG. 3(b), antennas A1and A2 closely face each other between non-contact interfaces 10 and 12,respectively. As shown in the figure, these antennas A1 and A2 areconnected to respective signal receivers (10-9, 12-9), also referred toherein as signal receiver circuits, and respective signal transmitters(10-8, 12-8), also referred to herein as signal transmitter circuits,which are configured to be controlled by respective controller circuits(10-7, 12-7). A spiral coil or a coupling capacitor electrode may beused as the near-field antenna (e.g., antennas A1 and A2), for example.As shown in FIG. 10(c), it may be also preferable to introduce ahigh-speed and large-capacity communication method such as so-called 5G,for example, enabling a high-speed and a large-capacity CT image datatransmission owing to the increased data transfer speed of giga (G) bitsper second or more. Further, the wireless power feeding and the wirelesscommunication system may be performed by sharing the same coil orantenna.

Controllers as described herein with reference to any exampleembodiments, and/or any portions thereof (including, without limitation,controllers 10-7 and 12-7) may include, may be included in, and/or maybe implemented by one or more instances of processing circuitry such ashardware including logic circuits; a hardware/software combination suchas a processor executing software; or a combination thereof. Forexample, the processing circuity more specifically may include, but isnot limited to, a central processing unit (CPU), an arithmetic logicunit (ALU), a graphics processing unit (GPU), an application processor(AP), a digital signal processor (DSP), a microcomputer, a fieldprogrammable gate array (FPGA), and programmable logic unit, amicroprocessor, application-specific integrated circuit (ASIC), and thelike. In some example embodiments, the processing circuitry may includea non-transitory computer readable storage device, for example a solidstate drive (SSD), storing a program of instructions, and a processor(e.g., a CPU) configured to execute the program of instructions toimplement the functionality and/or methods performed by some or all ofany of the controllers as described herein.

FIG. 3(c) is a flowchart explaining each step of the driving method forthe CT system according to at least one example embodiment. As shown inthe figure, after the movement of the gantry 5 and the start of rotationof the rotating part 23 (driving step S11), imaging by X-ray irradiationis started, such that the X-ray generator emits X-rays and the sensorarray 31 is subjected to X-ray irradiation by at least some of saidX-rays, such that one or more sensor units 30 of the sensor array 31generate one or more output signals, provided (e.g., via processing ofthe output signals by one or more circuits) as image data or digitaldata, in response to said X-ray irradiation (S12). The digital dataobtained from the sensor array 31 is recorded in the image memory 35 inreal time (S13). As shown in FIG. 2(b), the digital data can be recordedin the image memory 35 as the parallel data without parallel to serialconversion. After the image capturing is completed (S14), the gantry 5is stopped at a predetermined position in relation to the gantry table 7such that the rotating part interface 2-2 via the host interface 2-1 areface to face with each other and configured to be electrically connectedwith each other (e.g., via mechanical engagement of respectiveconnectors when the rotating part interface 2-2 via the host interface2-1 are mechanical interfaces, or interaction of electromagnetic fieldtherebetween when the rotating part interface 2-2 via the host interface2-1 are contactless interfaces) (S15), and the data recorded in theimage memory 35 is read from the rotating part interface 2-2 via thehost interface 2-1 (S16). The data read from the rotating part interface2-2 via the host interface 2-1 may be communicated to the control unit40-1 (e.g., via cable 40-3). The control unit 40-1 may perform an imagereconstructing process on said data. After the image reconstructingprocess is performed at the control unit 40-1, the control unit 40-1 maybe configured to cause an image based on said reconstructing process tobe displayed on the display monitor 40-2, followed by the CT systementering a standby state (S18). The lithium ion battery 27 may becharged (S17) at the same time as the driving step (S16) or during thestandby period (S18), and then the driving sequences is completed.

FIG. 4(a) is a plan view of the CT system 300, particularly showing theinside structure of the gantry 5-2, as viewed from the Z-axis directionaccording to at least one example embodiment. FIG. 4(b) is a crosssectional view of the gantry 5-2 used in the CT system 300 with a viewdirection of the X-axis or Y-axis. As shown in FIG. 4(a), in at leastone example embodiment, an X-ray generator 25 m, a rechargeable battery27 m, a high voltage control circuit 29 m, an energy recovery brakecircuit 50 which will be discussed below for example, are placed insidethe rotating part 23-2. On the other hand, many sensor units 30 mountedon the entire circumference are placed inside the annular fixed part 24having the same rotation center as that of the rotating part 23-2. Inthis example embodiment, the fixed part 24 is attached to the innerperipheral portion of the gantry 5-2 and is located inside the rotatingpart 23-2 as shown in the X-Y plan view. The gantry rotation motor 19and the timing belt 21 which rotates the rotating part 23-2 are alsodescribed. This setup may be like so-called Nutate-Rotate type CTsystem. As shown in FIG. 4(b), the X-rays (broken line arrow) emittedfrom the X-ray generator 25 m may be blocked by the fixed part 24, andtherefore fixed part 24 is shifted in the Z-axis direction with respectto the mounting position of the sensor unit 30. The X-ray generator 25m, the rechargeable battery 27 m, the high voltage control circuit 29 m,the image memory 35 m, and the sensor driving and control circuit 41 mare cartridge type structure, which can be easily attached or detached,as will be described in detail below. With this configuration, thesystem operation rate is improved, available imaging time is extended,and the system maintenance load is reduced.

FIG. 4(c) is a cross-sectional view of the internal structure of the CTsystem according to a variation of the above example embodiment shown inFIG. 4(b), particularly shows the internal structure of the gantry 5-2.The fixed part 24 and the rotating part 23-2 are incorporated inside thegantry 5-2. The difference from the structure shown in FIG. 4(b) is thatthe diameter of the rotating part 23-2 containing the X-ray generator 25m is smaller than the diameter of the inner peripheral portion of thefixed part 24. The X-rays emitted from X-ray generator 25 m can reachthe sensor units 30 without being blocked by the fixed part 24. Thissetup may be like so-called Stationary Rotate type CT system. However,in the case of the conventional structure using a slip ring andelectrode brush, their contact surface may heat up causing seizure, andthe sensor unit 30 may make an erroneous photoelectric conversion ofincident X-rays due to a light emission phenomenon caused by an electricspark when a high voltage or large current flow is applied from thebrush electrode to the slip ring sliding with a high speed.

This configuration may cause non-uniform X-ray irradiation of the sensorunits 30 because the rotating part 23-2 is located opposed to the X-raygenerator 25 m in between the central axis of the rotation center and onthe optical path of the X-rays emitted from the X-ray generator 25 m. Astructure that solves this problem will be described below withreference to FIGS. 5(a)-5(d). FIG. 5(a) shows a plan view illustratingthe structure of the CT system 400 according to at least one exampleembodiment, particularly inside the gantry part, as viewed from theZ-axis direction. As described above, the fixed part 24 is combined tosurround the outer circumference of the rotating part 23-2. Sensor units30 (not shown in this figure) are arranged on the entire innercircumference of the fixed part 24. The rotating part 23-2 has an X-raygenerator 25 m, a light source drive circuit and a secondary batterywhich is also referred to herein interchangeably as a rechargeablebattery (not shown in this figure), for example. An opening 28 marked bya broken line A is formed at the rotating part 23-2, and defined by therotating part 23-2 so that the X-rays emitted from the X-ray generator25 m can transmit or pass therethrough. With this configuration,intensity of X-ray beam 26 and its traveling direction may not beaffected. The opening 28 does not necessarily have to be an empty spacewhere all the members are removed (air only), and a protective covermade of resin having a high X-ray transmittance, for example, may exist.FIG. 5(b) is a cross-sectional view of the structure inside the gantrywhen the opening 28 is viewed from the X-axis or Y-axis direction. Thesensor unit 30 is arranged along the inner circumference of the fixedpart 24, and the X-ray beam passing through the opening 28 reaches thesensor unit 30. A fiber optic plate which selectively shields orcollimates X-rays, and an X-ray scintillator, for example, may bestacked on the sensor unit 30.

FIG. 5(c) is an enlarged plan view seen from the Z-axis directionshowing the structure of the portion indicated by the broken lineportion A in FIG. 5(a). The sensor units 30 are closely arranged alongthe annular portion of the fixed part 24 so that the longitudinaldirection of the sensor units 30 are parallel to the Z-axis. That is, asshown in FIG. 5(d), the same portion will be described with reference toa plan view of the opening 28 being observed from the side of X-raygenerator 25 m. The pixel arrays of the plurality of sensor units 30attached to the fixed part 24 are directly exposed to the X-raygenerator 25 m through the opening 28 formed in the rotating part 23-2without shielding the X-ray irradiation.

With reference to FIGS. 6(a)-6(c), structure, arrangement andcombination of sensor unit 30 which may be suitable for the CT system300 or 400 will be described below. In FIG. 6(a), a plurality of sensorunits 30-1 are closely arranged along the inner circumference of thefixed part 24 as to surround the rotation center axis 1. The pluralityof sensor units 30-1 are contact with in between the boundary line30-14, and preferably, the arrangement pitch of the pixels 30-11 inbetween the boundary line is equal to the arrangement pitch of thepixels 30-11 being not contact with the boundary line 30-14 in the samedirection. The structure disclosed in the Japanese Patent No. 5027339,herein incorporated by reference in its entirety, for example may beadopted in such a case. Further, as shown in the figure, the verticalscanning circuit (30-12), and the horizontal scanning and the signalreadout circuits (30-13) are placed along the two sides opposite to eachother in order not to change the arrangement pitch of each pixel 30-11described above. Preferably, the sensor unit 30-1 has a larger chipsize, and then so-called medium format size (44 mm×33 mm), full formatsize (36 mm×24 mm) and APS format size (23 mm×15 mm) sensor units whichare widely used in digital cameras, for example, can be used based on oroptimizing their structure and manufacturing method of CMOS type sensorunit.

FIG. 6(b) discloses a configuration where a plurality of sensor units30-2 are closely arranged along the inner circumference of the fixedpart 24 as to surround the rotation center axis 1 and further arrangedin the direction of the rotation center axis 1 in order to increase thetotal number of pixels in the direction of body axis (Z-axis). With sucha configuration, the slice width can be enlarged twofold. In at leastone example embodiment, the boundary line 30-24 between the left sensorunit 30-2 and the right sensor unit 30-2 in the figure should beconsidered, because the arrangement pitch of the pixels 30-21 in betweenthe boundary line 30-24 should be equal to the arrangement pitch of theother pixels 30-21 not facing the boundary line 30-24 in the samedirection. As already explained above, the structure disclosed inJapanese Patent No. 5027339, herein incorporated by reference in itsentirety, may be adopted in such a case. As shown in the figure, thevertical scanning circuit (30-22), and the horizontal scanning and thesignal readout circuits (30-23) are placed along the one side of thesensor unit 30-2 in order not to change the arrangement pitch of eachpixel 30-21 along the other three sides of the sensor unit 30-2. Threeor more sensor units 30 must be arranged in the body axis (Z-axis)direction in order to expand the slice width further. In such a case,the horizontal and vertical scanning circuits and the signal readoutcircuit (30-22, 30-23) may change the arrangement pitch of the pixels30-21. An example solution to solve this problem is disclosed inJapanese Patent No. 5424371, herein incorporated by reference in itsentirety.

FIG. 6(c) is a cross sectional view of the sensor unit 30-2 as shown inFIG. 6(b). The sensor unit 30-2 is a backside illuminated CMOSsolid-state image sensor having a scintillator layer 22 laminated on thebackside. The silicon substrate used in this CMOS solid-state imagesensor may be about 5 to 10 micron meter (μm) in thickness because theincident X-ray 26 is converted into a visible light 26 v in thescintillator layer and the visible light 26 v is read out as an electricsignal by each pixel 30-21. A wiring layer 30-27, horizontal andvertical scanning circuits, signal readout circuits (30-22, 30-23), andconnection terminals 30-26 are provided on the front side of the sensorunit 30-2. On the back side, a shield member 30-25, which can reduce theX-ray intensity of incident X-rays and protect the integrated circuitfrom X-ray damage, is laminated on the horizontal scanning, verticalscanning and the signal readout circuits (30-22, 30-23, respectively).

FIG. 7(a) shows a side view of the CT system 500 as viewed from theX-axis direction according to at least one example embodiment. The CTsystem 500 comprises a bed 3-1, a bed supporting member 3-2 for movingthe bed 3-1 and an annular gantry 5. As described above, the gantry 5has the rotatable rotating part 23 inside, and the rotation center axis1 is parallel to the Z-axis, or the body axis direction. A fixed part 24is placed around the rotating part 23 using a ball bearing (not shown inthe figure), for example. A portion B surrounded by a broken line withrespect to the rotating part 23 and the fixed part 24 will be discussedin detail below. An operation or control unit 40-1 and a display(monitor) unit (display monitor 40-2) (shown in FIG. 1(a)) are provided,and a reconstructed tomographic image generated by an image processingcircuit and software (which may be implemented by the control unit 40-1in any of the example embodiments) based on image data provided based onoutput signals generated by the sensor array 31 in response to X-rayirradiation may be displayed on the display monitor 40-2. The structuresof the rotating part 23 and the fixed part 24 of the CT system 500 maybe the same as those of the CT system 300 (in FIGS. 4(a)-4(c)) or the CTsystem 400 (in FIGS. 5(a)-5(d)) as explained above.

FIG. 7(b) is a plan view of the CT system 500 seen from the Z-axisdirection. Inside the annular portion of the gantry 5, a rotating part23 that rotates around the rotation center axis 1 is installed usingball bearings. A timing belt 21 for rotating the rotating part 23 and arotating part drive motor (rotating motor 19) are installed. As will bedescribed below, a direct drive (DD) motor configuration may be usedsuch that the rotating part 23 acts as a rotor and the innercircumference of the gantry 5 surrounding the rotating part 23 acts as astator. FIG. 7(c) shows an enlarged view of the portion B in FIG. 7(a),and the rotating part interface 6-1 made of a metal electrode is formedon the side surface of the rotating part 23. The rotating part interface6-1 is located at a position facing the host interface of the convextype connection terminals 4 (also referred to herein as connectors,connector electrodes, or the like), and then the rotating part interface6-1 can be electrically connected by contacting each other when therotating part 23 is stationary. Preferably, a position sensor (not shownin the figure) using a Hall effect position sensor, for example may beused so that the convex connection terminal 4 and the rotating partinterface 6-1 are stopped at a position facing each other, such that therotating part interface 6-1 and the convex connection terminal 4 of thehost interface 2-1 are face to face with each other as described herein.Alternatively, if the rotating part interface 6-1 is formed in a ringshape over the entire circumference of the annular side surface of therotating part 23, the rotating part interface 6-1 and the convex typeconnection terminals 4 may be electrically connected regardless of thestationary position of the rotating part 23.

According to at least one example embodiment, the rotating part of theCT system 600, particularly inside the gantry 5 will be described withreference to FIGS. 8(a)-8(c). FIG. 8(a) shows a plan view of therotating part 23 inside the gantry 5 as seen from the Z-axis direction,and FIGS. 8(b) and 8(c) show the enlarged structure of the broken lineportion 39 in FIG. 8(a). As explained above, the rotation part 23 hasthe X-ray generator 25, the rechargeable battery 27, the high voltagecontrol circuit 29, the sensor array 31, the sensor peripheral circuit33 including the signal amplification, AD conversion circuit, the signalscanning and control circuit, for example. The sensor driving andcontrol circuit 41, a non-contact interface 12, and a digital signalprocessing circuit (not shown in the figure), a parallel to serialconversion circuit (not shown in the figure) are also incorporatedinside the rotation part 23. As will be described below, the energyrecovery brake circuit 50 is placed in the fixed part or the rotatingpart 23 inside the gantry. The electromagnetic induction coil 36-1,which may in some example embodiments refer to a plurality of inductioncoils is provided around either the rotating part 23 or the fixed part.The energy recovery brake circuit 50 utilizes the electromotive forceinduced in the electromagnetic induction coil, to convert anelectromotive force in the electromagnetic induction coil 36-1, inducedby a moment of inertia about the rotating part 23, into electric energy.

In the structure (39-1) of FIG. 8(b), for example, the N pole and the Spole of the permanent magnet (34-1) are alternately arranged along thering-shaped side of the fixed part so that N poles and S poles of thepermanent magnets are alternately facing the annular part of therotating part. On the side of the rotating part, the induction coil(s)(36-1) is/are wound around the iron core(s) (32-1). Therefore, theenergy recovery braking circuit 50 may be provided inside the rotatingpart 23. On the other hand, in the structure (39-2) of FIG. 8(c), forexample, the N pole and the S pole of the permanent magnet (34-2) arealternately arranged along the ring-shaped side of the rotating part sothat N poles and S poles of the permanent magnets are alternately facingthe circumference of the fixed part. On the side of the fixed part, theinduction coil(s) (36-2) is/are wound around the iron core(s) (32-2).Therefore, the energy recovery brake circuit 50 may be provided insidethe fixed part. This structure may be like that of so-called a directdrive (DD) motor, which is not necessary to rotate the rotating partusing an external motor and a timing belt. The structure shown in FIG.8(b) may be preferable if electric energy is stored in the rechargeablebattery 27 inside the rotating part 23 or an electric double layercapacitor as described below. In the structure of FIG. 8(b), anelectromotive force is generated in the induction coil (36-1) even whenthe rotating part 23 is forcibly rotated by an external motor via atiming belt, as described below, and then it is also possible to chargethe rechargeable battery 27. Even after providing the forcible rotationdescribed above, the rotational energy generated in the induction coil(36-1) is recovered to the rechargeable battery or an electric doublelayer capacitor until the rotation stops as discussed in detail below.

Preferably, a neodymium magnet, for example, may be used as thepermanent magnet. As will be described below, the rotational movement ofthe rotating part inside the gantry is unnecessary after the imagingoperation is completed. However, it may be possible to convert themoment of inertia of the rotating part into an electric energy withoutstopping the rotary motion mechanically, and then energy saving effectcan be obtained. The energy recovery brake circuit 50 has such a role inthis example embodiment. Rotation (imaging mode) and stop (standby mode)motions are frequently repeated, so that the above mentioned rotationenergy recovery effect of the rotating part is remarkable, particularly,in the case of high-speed scanning with increasing the number ofrotations of the rotating part.

The energy recovery brake circuit 50 is described below with referenceto FIG. 9(a). In the CT system according to at least one exampleembodiment of the inventive concepts, the imaging operation starts afterthe rotation of the rotating part 23 starts. The imaging operation mayinclude the X-ray generator generating X-rays to irradiate the sensorarray 30, such that the sensor array 30 generates one or more outputsignals in in response to X-ray irradiation thereof by the X-raygenerator 25, where said output signals may be processed to provideimage data, also referred to herein as digital data. The rotation of therotating part 23 decelerates, and then the rotational motion stops aftercompleting the imaging sequence. As described above, rotation start andstop motions are repeated within a short time and imaging operations.Effective reuse of the rotational kinetic energy of the rotating part 23may reduce the power consumption of the rechargeable battery 27 and saveenergy. The energy recovery brake circuit 50 provided inside therotating part 23 may include a bidirectional DC-DC converter 42connected to the rechargeable battery 27, and a DC-AC converter 46connected to the other end of the bidirectional DC-DC converter 42. Theother end of the DC-AC converter 46 is connected to the induction coil36. The induction coil 36 is connected to a capacitor, preferably anelectric double layer capacitor 44, via an AC-DC converter 48. Further,the electric double layer capacitor 44 is connected to the bidirectionalDC-DC converter 42. The rotary kinetic energy of the rotating part 23can be converted into counter electromotive force generated in theinduction coil 36, which can charge the electric double layer capacitor44. Also, the rechargeable battery 27 can be charged via thebidirectional DC-DC converter 42. In general, the energy recoveryefficiency using a capacitor may be about 90% or more, which may behigher than that of the case using a rechargeable battery of around 60%efficiency. Particularly, with this configuration, it may be useful forthe CT system in which the rotating part 23 is decelerated (energyrecovery) and is immediately rotated (discharged) repeatedly. Withrespect to the bidirectional DC-DC converter 42, a circuit system inwhich a step-down chopper circuit and a step-up chopper circuit arecombined, or a PWM (Pulse Width Modulation) system using a DSP (DigitalSignal Processor) and an AD converter may be used.

FIG. 9(b) is a flowchart describing the driving method when the energyrecovery brake circuit is used like the example embodiment shown inFIGS. 8(a) and 8(b), for example. As shown in the figure, after therotation of the rotating part 23 is started, then the bed or the gantrybegins to move (driving step S21). In the next step, imaging by X-rayirradiation (e.g., the imaging operation) proceeds (S22). The imagingoperation may include the X-ray generator generating X-rays to irradiatethe sensor array 30, such that the sensor array 30 generates one or moreoutput signals in in response to X-ray irradiation thereof by the X-raygenerator 25, where said output signals may be processed to provideimage data, also referred to herein as digital data. In some exampleembodiments, the sensor array 31 may generate output signals that arethe aforementioned digital data and/or image data without additionalprocessing. The digital data obtained from the sensor array 31 isrecorded in the image memory 35 in a real time manner (S23). Asdescribed above, digital data can be recorded in the image memory 35 asparallel data without converting the data from parallel to serial. Afterthe imaging is completed (S24), the rotational kinetic energy of therotating part 23 causes a counter electromotive force in the inductioncoil(s) to be recovered as an electric energy, and the rotationalmovement is decelerated while charging the capacitor or the rechargeablebattery 27 (S25). Finally, the gantry stops at a predetermined position(S26) such that the rotating part interface and the host interface areface to face with each other and configured to be electrically connectedwith each other, the data recorded in the image memory 35 is read fromthe rotating part interface through the host interface (S27), and theimage is reconstructed by the operation and control unit 40-1. The dataread from the rotating part interface 2-2 via the host interface 2-1 maybe communicated to the control unit 40-1 (e.g., via cable 40-3). Thecontrol unit 40-1 may perform an image reconstructing process on saiddata. After processing, the resulting (e.g., shooting) image is causedby the control unit 40-1 to be displayed on the display monitor 40-2. Inparallel, the rechargeable battery 27 is charged (S28), and then aseries of sequences is completed to enter the standby state (S29). Aswill be described later and not shown in the flowchart, it may be alsopreferable to add a step in which the used rechargeable battery 27 isdisconnected and an already charged rechargeable battery is mountedinstead when the gantry stops at a predetermined position and returns tothe next imaging step (first step of the flowchart).

FIG. 10(a) is a cross-sectional view seen from the X-axis directionshowing the gantry portion of the CT system 700 according to at leastone example embodiment. The X-ray generator 25 m, which is a componentincorporated in the rotating part 23, should be replaced correspondingto the frequency of use due to the deterioration of the target member,and consumption of the electron beam generating cold cathode materialsor carbon nano materials in this example. Similarly, the sensor array 31m may also need to be replaced due to the radiation damage to thesemiconductor components used or the humidity dependency of thelaminated X-ray scintillator material. Therefore, in at least oneexample embodiment, the X-ray generator 25 m and the sensor array 31 memploys cartridge form, which is detachable from the rotation part 23.As shown in FIG. 10(a), the rotating part 23 is provided with acartridge receiving spaces 25 f and 31 f (both indicated by broken lineportions) into which the cartridge types X-ray generator 25 m and thesensor array 31 m are inserted. The X-ray generator 25 m and the sensorarray 31 m are inserted and removed in the Z-axis or the body axisdirection, and the openings for inserting or removing the cartridges arefaced in the Z-axis direction. It may be suitable for the cartridge formto be used in the case having the above mentioned cradle structure (FIG.3(a)) for example, when an old cartridge is replaced with a newcartridge kept in the cradle side. The cartridge form is not limited tothe X-ray generator 25 m and the sensor array 31 m, but as describedabove (FIG. 4(a), for example), the rechargeable battery 27, or an imagememory 35 according to the increase in recording capacity may have sucha cartridge form.

FIG. 10(b) is a plan view showing the rotating part 23 of the CT system800 as seen from the Z-axis direction, according to at least one exampleembodiment. As will be described below in detail, the energy recoverybrake circuit 50 may be incorporated inside the rotating part 23. In atleast one example embodiment, in addition to the image memory 35, andthe rechargeable battery 27, the first X-ray generator 25 and the secondX-ray generator 25-2 are provided, and a first sensor array 31 and asecond sensor array 31-2 are placed on the opposite sides of these X-raygenerators via the central axis 1. The sensor array 31 or the sensorarray 31-2 may be arranged at positions shifted in the Z-axis direction.Further, the X-ray generator 25 and the X-ray generator 25-2 may emitX-rays at the same time or with a different timing. Furthermore,different X-ray tube voltages (or wavelengths) can be applied to theX-ray generator 25 and the X-ray generator 25-2 to perform multispectralanalysis. As mentioned above, the X-ray generators 25, 25-2, the sensorarrays 31, and 31-2 may also have a cartridge form. With theseconfigurations using the cartridge form for the main parts inside therotating part 23, it enables not only reducing the maintenance load suchas parts replacement or repair but also extending the operation time ofthe system. It should be also noted that extremely useful functions andeffects such as versatility of imaging and inspection like themulti-spectral image analysis or these hybridizations are realized.

FIG. 10(c) is a side view of a CT system 900 as seen from the X-axisdirection according to another example embodiment. Two gantries (gantry5 and gantry 5-2) are mounted on the gantry table 7 having two cradles(9-3 and 9-4). The cradle 9-4 has a donut-shaped hollow structure sothat a subject and a bed (not shown in the figure) can pass through thehollow structure. The CT system 900 enables various examinations by themultiple gantries such as a combination of X-ray CT inspection gantryand PET (positron emission tomography) inspection gantry, or combinationof X-ray CT inspection gantry and near infrared diffused light imaginggantry. Further, a protective cover 51 is provided above the gantrytable along the moving direction of the gantry in order to prevent thesubject or the object to be examined from coming into contact with thegantry during the movement of the gantry. The plurality of gantries canbe driven individually or in conjunction with each other. Preferably, ahigh-speed wireless communication interface may be introduced betweenthe gantry (40-6) or the rotating part (40-5) and the operationalcontrol part (e.g., control unit 40-1), (40-4), in order to monitoroutput signal like a fluoroscopic image of the subject from the rotatingpart or the gantry while the gantry 5, 5-2 is moving in the body axisdirection.

In some example embodiments, including the example embodiments shown inFIG. 10(c) but also any of the example embodiments, including theexample embodiments shown in FIG. 1(a), the control unit 40-1 mayinclude a wireless communication interface 40-4 (e.g., a 5G wirelessnetwork communication transceiver, an ad hoc wireless networkcommunication transceiver such as a Bluetooth® transceiver, or thelike), and the gantry 5 and/or a rotating part 23 of the gantry 5 mayinclude a corresponding wireless communication interface 40-6, 40-5,etc. (e.g., each of the wireless communication interfaces may be a 5Gwireless network communication transceiver, an ad hoc wireless networkcommunication transceiver such as a Bluetooth® transceiver, or the like)As shown in FIG. 10(c), the wireless communication interface 40-4 mayestablish one or more wireless communication links 61 with thecorresponding wireless communication interfaces 40-5, 40-6, etc. to thusestablish a wireless communication link(s) between the control unit 40-1and one or more gantries and/or rotating parts of the CT system. Data,including image data generated at a rotating part 23 and/or gantry 5,may be transmitted to the control unit 40-1 via one or more wirelesscommunication links 61. Control signals may be generated at the controlunit 40-1 and transmitted to the gantry 5 and/or rotating part 23 viaone or more of the wireless communication links 61. Such control signalsmay include control signals to cause the gantry 5 and/or rotating part23 to engage in movement, control signals to cause the gantry to performan imaging operation, some combination thereof, or the like. Therefore,in at least one example embodiment, the control unit 40-1 and at leastone gantry 5, 50-2 have respective wireless communication interfaces40-4, 40-5, 40-6, etc. configured to enable, by wireless communicationbetween the control unit 40-1 and the gantry/gantries 5, 5-2, at leastone of: transmitting and receiving a control signal to control movementof the gantry 5, 5-2 in the Z-axis direction by wireless communication,or causing the gantry 5, 5-2 to perform an imaging operation.

Example embodiments having thus been described, it will be obvious thatthe same may be varied in many ways. Such variations are not to beregarded as a departure from the intended spirit and scope of exampleembodiments of the inventive concepts, and all such modifications aswould be obvious to one skilled in the art are intended to be includedwithin the scope of the following claims.

What is claimed:
 1. A computed tomographic (CT) system, comprising: agantry including a rotating part, wherein the rotating part includes alight source, a light source drive control circuit, a rechargeablebattery, and a rotating part interface, wherein the gantry furtherincludes, inside or outside the rotating part, a detector, a detectorcontrol and signal processing circuit configured to drive the detectorand process an output signal from the detector, and an image memoryconfigured to record the output signal of the detector, wherein therotating part is configured to rotate around a central axis of a bodyaxis direction; a gantry table, the gantry mounted on the gantry table,the gantry table including a host interface; a motor configured to causethe gantry to move in relation to the gantry table in the body axisdirection between positions in relation to the gantry table within agantry moving range; and a control unit configured to process anddisplay image data obtained from the gantry, wherein the rotating partinterface is configured to face the host interface, such that therotating part interface and the host interface face each other and areconfigured to be electrically connected with each other, based on thegantry being at a predetermined position in relation to the gantry tablewithin the gantry moving range.
 2. The CT system of claim 1, wherein thepredetermined position is an end point of the gantry moving range. 3.The CT system of claim 1, wherein the rotating part interface and thehost interface are configured to face each other in a vertical directionbased on the gantry being at the predetermined position.
 4. The CTsystem of claim 1, wherein the rotating part interface and the hostinterface are configured to face each other in the body axis directionbased on the gantry being at the predetermined position.
 5. The CTsystem of claim 1, wherein the rotating part interface and the hostinterface are mechanical interfaces configured to be electricallyconnected based on being mechanically contacted with each other, basedon the gantry being at the predetermined position, or contactlessinterfaces configured to be electrically connected in a contactlessmanner based on an interaction of an electromagnetic field therebetween,based on the gantry being at the predetermined position.
 6. The CTsystem of claim 1, wherein the motor is inside the gantry.
 7. The CTsystem of claim 1, further comprising a drive motor configured to rotatethe rotating part in relation to the gantry, the drive motor beinginside the gantry.
 8. The CT system of claim 1, further comprising: acradle above an upper portion of the gantry table in a verticaldirection, the cradle being at the predetermined position in relation tothe gantry table, wherein the cradle includes the host interface.
 9. TheCT system of claim 1, wherein the light source is an X-ray light sourcethat includes an electron beam generating unit, the electron beamgenerating unit being composed of a carbon nanostructure material. 10.The CT system of claim 1, wherein the detector, the light source, thedetector control and signal processing circuit, and the image memory areinside the rotating part, and the detector and the light source are atopposite sides of the rotating part such that the central axis issandwiched between the detector and the light source.
 11. The CT systemof claim 1, wherein the detector is an electron multiplication sensor,an avalanche effect sensor, or a photon counting sensor.
 12. The CTsystem of claim 1, wherein the control unit and the gantry haverespective wireless interfaces configured to enable, by wirelesscommunication between the control unit and the gantry, transmitting andreceiving a control signal to control movement of the gantry in the bodyaxis direction by wireless communication, or causing the gantry toperform an imaging operation.
 13. The CT system of claim 1, furthercomprising a protective cover above the gantry table, the protectivecover extending along the body axis direction.
 14. The CT system ofclaim 1, wherein inside the rotating part, at least one of the lightsource, the detector, the rechargeable battery, or the image memory hasa cartridge form including electrical contacts, and the rotating parthas a cartridge receiving space into or from which the at least one ofthe light source, the detector, the rechargeable battery, or the imagememory having the cartridge form is configured to be inserted orremoved.
 15. The CT system of claim 1, further comprising a secondgantry on the gantry table.
 16. The CT system of claim 1, wherein thedetector includes a sensor array of sensors that are arranged over anentire inner circumference of a fixed part surrounding the rotating partinside the gantry.
 17. The CT system of claim 16, wherein: the rotatingpart includes an opening configured to allow light emitted from thelight source to pass therethrough in the rotating part, and the openingand the light source are at opposite sides of the rotating part suchthat the central axis is sandwiched therebetween.
 18. The CT system ofclaim 1, further comprising: a plurality of induction coils; permanentmagnets; and an energy recovery brake circuit configured to convert anelectromotive force in the plurality of induction coils, induced by amoment of inertia about the rotating part, into electric energy, whereinthe plurality of induction coils are arranged along an annular part ofthe rotating part, the permanent magnets are arranged along a fixed partof the gantry surrounding the rotating part so that N poles and S polesof the permanent magnets are alternately facing the annular part of therotating part, and the energy recovery brake circuit is in the rotatingpart, or the plurality of induction coils are arranged along acircumference of a fixed part inside the gantry surrounding acircumference of the rotating part, the permanent magnets are arrangedalong the circumference of the rotating part so that N poles and S polesof the permanent magnets are alternately facing the circumference of thefixed part, and the energy recovery brake circuit is in the fixed part.19. A method of driving the CT system of claim 18, the methodcomprising: causing the gantry to begin to move after rotationalmovement of the rotating part around the central axis has started;performing an imaging operation, the imaging operation including X-rayirradiation of the detector by the light source to cause the detector togenerate digital data in response to the X-ray irradiation; recordingdigital data obtained from the detector in the image memory based on theX-ray irradiation; causing a counter electromotive force in theplurality of induction coils to be recovered by the energy recoverybrake circuit as electric energy being caused by rotational kineticenergy of the rotating part, such that the rotational movement isdecelerated while the energy recovery brake circuit charges a capacitoror the rechargeable battery with the electric energy; causing the gantryto stop at the predetermined position, and causing the digital datarecorded in the image memory to be read from the rotating part interfacethrough the host interface.
 20. The CT system of claim 1, wherein therotating part interface is configured to face the host interface, suchthat the rotating part interface and the host interface face each otherand are configured to be electrically connected with each other, basedon the rotating part being rotated to a particular rotational positionwhere the rotating part interface is at a particular position to facethe host interface.